Morphology and taxonomic position of the Late Cretaceous diatom genus Pomphodiscus Barker & Meakin

Results from our investigation of Upper Cretaceous diatoms from the Marca S hale Member of the Moreno Shale in California and from Ocean Drilling Progr am (ODP) Hole 748C on the Kerguelen Plateau, Southern Indian Ocean enable a clarification of the taxonomic position of several diatoms. Differences in areola structure, a primary and conservative character of the diatom valve , are used to separate diatoms recently included in the genus Benetorus. We resurrect the genus Pomphodiscus to include species with locular areolae, a central rimoportula, and a central inflated chamber. We propose the new s pecies Pomphodiscus kerguelensis n. sp. and new combination Pomphodiscus cr aspedodiscoides comb, nov.